A palatable hyperlipidic diet causes obesity and affects brain glucose metabolism in rats

Debora Estadella,Gabriel I Souza,Claudia M Oller Do Nascimento,Eliane B Ribeiro,Allain A Bueno,Carlos A Habitante,Lila M Oyama,Caio Sm Motoyama

doi:10.1186/1476-511x-10-168

Abstract

BackgroundWe have previously shown that either the continuous intake of a palatable hyperlipidic diet (H) or the alternation of chow (C) and an H diet (CH regimen) induced obesity in rats. Here, we investigated whether the time of the start and duration of these feeding regimens are relevant and whether they affect brain glucose metabolism.MethodsMale Wistar rats received C, H, or CH diets during various periods of their life spans: days 30-60, days 30-90, or days 60-90. Experiments were performed the 60th or the 90th day of life. Rats were killed by decapitation. The glucose, insulin, leptin plasma concentration, and lipid content of the carcasses were determined. The brain was sliced and incubated with or without insulin for the analysis of glucose uptake, oxidation, and the conversion of [1-14C]-glucose to lipids.ResultsThe relative carcass lipid content increased in all of the H and CH groups, and the H30-60 and H30-90 groups had the highest levels. Groups H30-60, H30-90, CH30-60, and CH30-90 exhibited a higher serum glucose level. Serum leptin increased in all H groups and in the CH60-90 and CH30-90 groups. Serum insulin was elevated in the H30-60, H60-90, CH60-90, CH30-90 groups. Basal brain glucose consumption and hypothalamic insulin receptor density were lower only in the CH30-60 group. The rate of brain lipogenesis was increased in the H30-90 and CH30-90 groups.ConclusionThese findings indicate that both H and CH diet regimens increased body adiposity independent treatment and the age at which treatment was started, whereas these diets caused hyperglycemia and affected brain metabolism when started at an early age.

Highlights

Glucose is considered to be the major nutrient for cells of the adult nervous system
It was reported that high-fat diets, especially diets enriched with saturated fatty acids, impaired the learning and memory of rodents and that these effects could be related to insulin resistance and
We evaluated whether the time of the start and duration of these feeding regimens were relevant and whether they affected brain glucose metabolism

Summary

Introduction

Glucose is considered to be the major nutrient for cells of the adult nervous system. A small portion of glucose is used for biosynthesis pathways. Poor glucose metabolism has been related to memory problems [2]. It was reported that high-fat diets, especially diets enriched with saturated fatty acids, impaired the learning and memory of rodents and that these effects could be related to insulin resistance and Insulin receptors are expressed in several regions of the central nervous system [7,8]. According to Carvalheira et al [14], insulin modulates the leptin signal transduction pathway in the hypothalamus, playing a synergistic role in regulating food intake and controlling weight. We investigated whether the time of the start and duration of these feeding regimens are relevant and whether they affect brain glucose metabolism

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